One thing we did in the Silver Marches campaign was use my Bard character as the chronicler, which created an in-game "game journal" which I kept updated after each session. This way, all plot threads were kept track of. It's the most fun way to keep track and take notes I can think of - because you're creating a prop for an in-game document that also serves to keep the information fresh in players minds.
Sci-fi settings may not have bards, but chroniclers come in many forms. Indeed, the chronicles themselves may come from many sources. Perhaps part of a field captain's journal, scribbled on by scum, bookmarked and footnoted by imperials, etc.
I liked your dossier idea, but it needed more props - a scrap of cloth, dried flower, lock of hair, etc. They add realism, but more importantly, they make the players reach for the dossier more often - just as putting an in-character spin on the journal made reading over notes and recapping information more enjoyable; they looked forward to the next installment, rather than having to be prompted at the start of each session.
That's my two cents. Thanks for a very fun introduction to the warhammer world.